Top civil engineering interview questions with short answers for site and design jobs.
1. What does M20 concrete mean?
M stands for mix, and 20 is the characteristic compressive strength of 20 N/mm² of a 150 mm cube after 28 days of curing.
2. What is a slump test?
A test to check the workability of fresh concrete. Concrete is filled in a slump cone in layers, the cone is lifted, and the fall in height of the concrete is measured as the slump.
3. Why is curing of concrete important?
Curing keeps concrete moist so that cement hydration continues. It helps concrete reach its full strength and reduces shrinkage cracks.
4. What are the initial and final setting times of OPC?
As per Indian standards, the initial setting time of ordinary Portland cement should be at least 30 minutes and the final setting time should not be more than 600 minutes.
5. What is a bar bending schedule (BBS)?
A BBS is a table listing the bar mark, diameter, shape, cutting length, number and weight of reinforcement bars. It helps in cutting, bending and estimating steel.
6. What is the difference between a one-way and a two-way slab?
If the ratio of the longer span to the shorter span is more than 2, the slab mainly bends in one direction and is a one-way slab. If the ratio is 2 or less, it bends in both directions and is a two-way slab.
7. What is the water-cement ratio and why is it important?
It is the ratio of the weight of water to the weight of cement in a mix. A lower ratio gives higher strength and durability, but the mix must still be workable.
8. What are the common types of foundation?
Shallow foundations such as isolated, combined, strip and raft footings, and deep foundations such as pile and well foundations.
9. Why is clear cover given to reinforcement?
Cover protects steel from corrosion and fire, and gives proper bond between steel and concrete. The required cover depends on the member and exposure condition.
10. How are concrete cubes tested?
150 mm cubes are cast from the mix, cured, and tested in a compression testing machine, usually at 7 and 28 days, to check that the concrete reaches its required strength.
These are common questions asked in interviews for freshers and experienced candidates. Read each topic in your textbook for full details. See the latest jobs on our homepage.